I don't think artists inherently have more opportunities than writers do Perhaps in Tapas which has been established as a webcomic site much longer than novel feature added, artist do have more opportunities (plus the emphasize of visual here); but that doesn't meant generally artists are more lucky or privileged in general.
Writer can demand payment from their work too! There are paid collabs here looking for writer, not the majority but there is! I meant to make comic, story (or content) is very fundamental and should be paid attention more.
No matter how good the art, I will drop a comic if the story sucks; I can browse gallery to merely enjoy good art, and if you even dare to make a comic better prepare a solid content (It icks me when people think their comic with bad story will be saved by good art. No, make an artbook instead, sorry not sorry.)
Not all artist can make a good story despite how much they want to make a comic. Also there are many great comic with questionable art but doing good mainly because of the story/ content. That means writing skill is very much needed, you deserve to be paid and appreciated as a writer! Especially in professional work, there's no way you won't get paid as a writer! You can work at many sectors; from making children book, horror movies, to political propaganda for Supreme Leader! And it should be equal to work you spent on; if you spent more work portion than the artist, you should get paid more.
I'm more of an artist that a writer, but I only write novel here. Do you know why? Because writers are so lucky they don't need to draw!